Effect of Oxypropylene Chain Length on the Surface Properties of Dialkyl Glycerol Ether Nonionic Surfactants

Abstract

In this work, as a continuation of our studies concerning the preparation and surface properties of nonionic surfactants, derivatives of 1,3-dialkoxy-2-propanols and 1,3-dialkoxy(oligooxypropylene)-2-propanols with oligooxypropylene chains have been synthesized and investigated. The surface activity of these compounds has been determined, i.e., critical micelle concentration (CMC), surface excess concentration (Γ), surface area demand per molecule (A), surface tension at CMC (γCMC), ΔGads°, and ΔGmic°. A linear decrease of the log CMC vs number of oxypropylene groups is observed, and based on the Shinoda equation the work of cohesion per oxypropylene group when passing from molecular to micellar state is calculated for 0.43 kT. The equivalent of CH2 in the aliphatic alcohol group is ca. 2.50 oxypropylene units. Surface properties of these surfactants, i.e., cloud point, wetting ability, contact angle, foam height, and emulsion stability type (O/W), have been determined as well.